Double-image microscope



Dec. 8 1925 A. KONIG DOUBLE IMAGE MICROSCOPE Filed March 19, 1924 Z SheetS-Sheet 1 Dec. 8, 1925- A. KONIG nousma: IMAGE MICROSCOPE Filed March 19, 1924 2 Sheets -Sheet 2 FJC L,

9 W a y F m.

Fig. 14

Patented Dec. 8, 1925;

UNITED, STATES PATENT OFFICE.

ALBERT Rome,

OF J'ENA, GERMANY, ASSIGNOR IO THE ITEM CARL ZEISS, 01B JENA,

GERMANY.

DOUBLE-IMAGE MICROSCOPE.

Application filed Karen 19, 1924. Serial No. 700,373.

To all 'whomz't may concern.

Be it known that I, ALBERT KZSNIG, a citizen of Germany, and residing at Jena, Germany, have invented a new and useful Double-Image Microscope (for which I have filed an application n Germany, March 31st, 1923), of which the following is a specification.

A well-known resource for the micro- 1 scopic measurement of distances is the double-image microscope with which the images of the two extreme points of the distance to be measured are optically brought into coincidence and whereby the amount of the relative rotation or displace ment of the optical members, which is requisite for the coincidence of the two images, furnishes the value sought for. \Vith' the usual constructional forms of such 2 an instrument the principal rays of the imaging raypencils, facing the object,'are convergent. This, however, has the drawback that slight displacements of the microscope in its axial direction, i.'e.' inexact ,2! focussing of the instrument. on the object, bring about an alteration of the relative position of the images of two imaged points owing to the convergence of the rincipal rays in the object-space, and there ore a rotation of displacement ofv optical members of the double-image microscope, corresponding to a wrong adjustment, may be necessary in order to bring the two images into coincidence. Accordingly the value,

ascertained from the amount of rotation or displacement, of the distance of the two points, viz the distance to be. measured, may show an undesirable measuring error. The object of the present invention is to eliminate this error and to provide an instrument adapted for the measurement of distances (e. screw-threads or graduations). g v The solution of the task set is attained by making use of the well-known idea to cause the path of the principal rays of the imaging pencils to be parallel when facing the object. If, as in the present case, the measurement only refers to distances, i. e.

! linear'magnitudes, it suifices to caus'ethe' principal rays of the pencils facing the object and imaging the extreme points of the...

distance to be measured, town in parallel in their projection upon a plane parallel The principal rays of centres of su tably choosing to thepptical axis of the microscope and determined by the distance to be measured. the pencils facing the image are then convergent and intersect in the same projection at one point of the image plane of the microscope, whereby the effect of inexact focussing of the microscope is dispensed with.

From the conver ence of the principal rays of the pencils acing the image it follows that, although the projections of the cross sectlons of the pencils coincide in the image plane at one point, there is produced by each pencil an exit pupil, whose projec tions are the more apart, the longer is the distance to be measured. Hence, owing to the restriction of the size of his eye-pupil to a diameter of a few mil imeters, the observer may in certain cases be unable to simultaneously see the coinciding images of the extreme points of the distance to be measured. Apart from this, the fact that the imaging pencils strike parts of the pupil of the eye which. are comparatively far apart may lead to errors owing to the irregularities of the eye. The principal rays of the imaging pencils which, when emanating from the common image point in the image plane of the microscope, tend to the gravity of the. two exit pupils, diverge on their path'from the image plane to the ocular. A focussing of the ocular on a plane, deviating from the image plane, or a d'ifierent accommodation of the eveio'f the observer entails therefore a change of the apparent position of the images of the expoints of the distance to be measured and may be the cause of an error: in measur ing. In order to avoid this "erroryit is possible tofurther improve the apparatus by parts of the microscope in such a way that the principal rays of the pencils, imaging the extreme points of the-distance to be measured, coincide on the image-side in the projection upon a plane, parallel to the optical axis 0 the microscope and determined by the distance -to be measured. The rojections of the exit 1pupils will then overap' eachother in eac position of the extreme pcints of the distance to be measured.

The annexed drawing shows five construe tional examples of the new instrument. Figs. 1' to 3 show the first example; Fig. 1

and disposing the optical is a longitudinal view, Fig. 2 is a cross section on the line 22 of Fig. 1, Fig. 3 shows in an elevation the position of the exit pupils. Figs. 4 and 5 show the second example; Fig. 4 is a longitudinal view, partly in a section, Fig. 5 shows in an elevation the position of the exit pupils. Figs. 6 to 8 illustrate the third example; Fig. 6 is a longitudinal View, Fig. 7 is a cross section on the line 7-7 of Fig. 6, Fig. 8 shows in an elevation the position of the exit pupils. F gs. 9 to 11; Show the fourth example; Fig. 9 1s a lon itudinal view, Fig. 10 is a cross section on e line 1010 of Fig. 9, Fig. 11 shows in an elevation the position of the exit pupils.

Figs. 12 to 14 show the fifth example; Fig. 12 is a longitudinal View, Fig. 13 is a cross section on the line 13-13 of Fig. 12, Fig.

14 shows in an elevation the position of the exit pupils. y

In the first example (Rigs. 1 to 3) the instrument is adjusted to the extreme points A andB-of a distance to be measured. The objective-s stem consists of two uniform front 'mem ers a and 21 which are opposite 1y movable in the direction of the distance to be measured and the distance apart of whose centres at any onetime is assumed to be read off on an indicating device consisting of a scale a and indices 0, and of a rear member I). The front members are constructed as semi-lenses so as to be capable of also being used for measuring very short distances. For the observation of the image produced by'the objective system use is made of an ocular, consisting of a field lens 0 and an eyelens (1. Owing to the shape of the semilenses a and a (see Fig. 2) the imaging ray pencils, emerging from the points A and B, have a semi-circular cross section and their principal rays traverse the semi-lenses at two points C and D which correspond to the centres of gravity of the semi-circular surfaces. As required by the inyention the path of the principal rays is, when facing the object, parallel in the projection represented in Fig. 1. Between the lenses of the objective-system a and a respectively and b the imaging pencils consist of parallel rays. Supposing the focussing is correct,

the distance to be measured AB must accordingly lie m the common front focal plane" of the semi-lenses a and a and the image plane,which is intersected by the pencils ata point E, in the rear focal plane of the back member The pencils intersect at the point E and "form two semi-circular. exit pupils e and 6 which are'represented in Fig 3 on an enlarged scale and whose centres of gravity F and G again form the points of intersection of the principal rays. In order to measure a distance, the microscope must be focussed in such a manner that the two extreme points A and B of the distance are sharply imaged Into a plane principal rays ofthe two imaging pencils of which is perpendicular to the microscope axis at the point E and on which plane the ocular is focussed. Thereupon one displaces the images of both points by altering the distance apart of the two semi-lenses a and a until they coincide at one point. In that case the distance of the ccntresof the lenses corresponds to the length sought for of the distance to be measured.

In the second example (Figs. 4 and 5) there is screwed to the bottom of a cylindrical microscope body 7 an objective lens 9 with its mount 9 which terminates in a diaphragm g disposed in the rear focal plane. Inside the microscope body 7' so there is a cylinder h provided with a rack, which forms the mount of a double wedge of glass it and which can be moved in the axial direction of. the microscope by means of a pinion f and atoothed wheel F. The amount of this motion can be read off by means of an index 7 on a scale f fixed on the pinion f At the top of the microscope body f is an ocular extension f with a field lens 0 and an eye lens (l. The pencils of the imaging rays of the extreme points A and B of a distance to be measured, on which the microscope is focussed, have a circular cross section owing to their beingconstricted by the diaphragm '9'. Their principal rays travel in parallel in the obj ect-space and traverse the diaphragm g at its centre H. The pencils are reflected towards each other by the double wedge h and image the points A and B on the image plane perpendicular at a point B to tlfe microscope axis. They produce two exit pupils e and e which are represented in Fig. 5 on an enlarged scale. These exit pupils have a circular cross section and are intersected by the principal rays at two points F and G which coincide with the centres ofthe circles. If the scale f be so gauged that the pointer indicates at any one time the distance, corresponding to the position of the inner cylinder 5? between the principal rays facing the object, the amount of the distance to be measured can be easily read off if the images of the extreme points A and B be brought into 00- incidence at the point E. Instead of' the 115 displaceable double wedge [2 it would also be possible to use in a known way two rotatable,-plane-parallel plates which may be rolie 'tated about axes perpendicular to the microj'ective, they are yet sensitive to inexact focussing with theflocular on the image lying 12 in the image plane. The following three examples represent such constructions of the new instrument which do not have this drawback because in the image-space the the extreme points of a distance to a ured coincide at any one time,in the tion upon a planeparalleltothe microscop:

axis and determined by the distance measured.

In the third example (Figs. 6 to 8) the ob-' j ective system of the microscope consiets" o .a front member a and two equal, semi-circular rear members 6 and b? which are op-, positely movable in the 'direction'of the distance to be measured and the distanceeapart of whose centres at any one time is assum' to be read off on an indicating device simi-.

lar to that shown in Fig. 1'.- These rear members are plano-convexcollective lenses and "iie with their plane surface in the focal plane of the front member a in which, there whose centre" 1 is also fixed a diaphragm H lies in the optical axis 0 e microscope. The observation is efiected with the aidof an ocular c, '(l. The principal rays of the imaging pencils of the two extreme points A and B of a distance to be measured are parallel in the object-space in the projection of Fig. 6 and have a semi-circular cross sec tion which,'on the one hand, is required b the diaphragm g and, on the other han by the boundary surface of the two semilenses 6 and b L The otherhalves of the two pencils are deflected from the microccopo'axis by the semi-lenses. -They are not shown in the drawing and are of no importance for the imaging. The principal rays of the imaging penclls emer 171 from the points A and B'traverse the iap iragm g and the semi-lenses b and b at two points. J and K which are different from the centre of the diaphragm H andcorrespond to the centres of gravity of half the diaphragm surfaces, separated by theboundar of the semi-lenses b and b. 8n their further ath the pencils intersect at a point E and orm two semi-circular exit upils c and e which are represented in ig; 8 on an enlarged scale and whose centres of gravity F and G again form the points. 0 intersection of the-principal rays. Whenmeasuring; the microscope is to be focussed in such away that the'two extreme points A andB are sharply imaged in a plane, which is per endicular' to the microscope axis at the point E and on which the ocularis focussed. .If the indicating device be so gauged as to'indicate at any one time the distance apart of the principal-rays facing the object and corresponding to the distance apart ofthe centres of the semi-lenses b b it is possible to easily read as the length of the distance to be measured if the images of the points A and B are brought into coinciden'ce at the oint E by altering the dis-- tance apart of t e t wo semi-lenses.

The fourth and the fifth example (-Figsl 9 to 11 and 12 to 14) show improvements of the first constructional example. In both f to Figs. 9 to 11 the of a twofol .tion b each in three isosceles-rectangu- 'lar pr sms n, n and o,

ciding with the centres of 'gravity'F an of these surfaces, are indicated. The meassurface 4 distance to and of these examples between the front members a and a respectively and the rear member 12, between which the imaging vpencils have parallel rays, there are interposed rismswhose construction may be seen from igs. 10 and 13. In the example according ppncil, traversing the semi-lens a, undergoes y means of four isosceles-rectangular fold reflection wit a deflection'by 90 each,

so that it enters the rear lens 5 in'parallel ed: --to itself and the pencil traversin the semirlsms a, is, Z and m a sixlens a. The semi-lens a with t e prisms and k is displaceable in the direction of thedistance to be measured and the distance of its centre from the centre of the fixedsemilens a is assumed to be read off on an indicatin device similar to that shown in Fig. 1. In t e example according to Figs.'12 to 14 both pencils parallel to each other are reflected-1n arallel to themselves by means 5 reflection each with a deflecrior to their traversingthe rear lens b. ith this arrangement the semi-lens a with the prism a is dis; laceable in the direction of the distance to e measured and the distance at any one time of theircentrefrom the centre of the fixed semi-lens a is again assumed to be 96 read off on an indicating device. The pa rs of semi-circular exit pupils e and e resultin in either case are represented in Figs. 11 an .14 on an enlarged scale and the points of intersection of the princlpal rays,'co1nuring process corresponds to the process set forth in the first constructional example.

IXclaim:

.1. In a miscroscope for measuring distances o tical means'adapted to produce an image 0? each of the extreme points of the be measured,'means adapted toalter the distance a art of the two images i in a direction paral e1 to the said distance,

means adapted-to separate from the rays, emerging from the said extreme'points, such rays that the I incipal rays of the two pencilsformed t ereby emanate in parallel o each other from the said extreme points and in a direction paral e1 to the said distance,

means adapted to separate from the rays,

emerging from the sa1d extreme points, such rays that the principal rays of the two pencils formed thereby emanate in parallel to each other from the said extreme points, and an indicating device adapted to indicate the distance apart of the said two images in a direction parallel to the said distance.

3. In a microscope for measuring dis- I tances optical means adapted to produce an image 0 each of the extreme pointsof the distance to' be measured, means adapted to alter the distance apart of the two images in a direction parallel to the said distance, means adapted to separate from the rays, emerging from the said extreme points, such rays that the principal rays of the two pencils formed thereby emanate in parallel to each other from the said extreme points and perpendicular to the direction of the said distance and strike the image plane of the microscope at the same point in the projection upon a plane parallel to the said distance and perpendicular to the said image plane, and an indicating device adapted to indicate the distance apart of the said two images in a direction parallel to the said distance.

4. In a microscope for measuring distances two front lenses disposed side by side and displaceable relatively to each other, a collective lens disposed behind the two front lenses and adapted to receive the rays emerging from the front lenses, an ocular disposed behind the said collective lens, and an indicating device adapted to indicate the distance apart of the axes of the said front lenses. I

5. In a microscope for measuring distances two front lenses disposed side by side and displaceable relatively to each other, a reflecting system, disposed.v behind the two front lenses and adapted to deflect the traversing luminous rays in such a waythat the principal rays of the ray pencils emerg mg from the front lenses are parallel to each other behind the reflecting system in the projection nppn a plane, which contains the rays coinciding with the axes of the front lenses, a collective lens dis osed behind the. reflecting system and an mdicating deviceadapted toindicate the distance apart of the axes of the said frontlenses.

6. In a microscope for measuring 'distances two front lenses disposed side b side and dis'placeable relatively to eachot er, a reflecting system, disposed behind the two' front lenses and adapted to deflect the traversing luminous rays in such a way that the principal ra s of the ray pencils emerging from the fli'ont lenses are parallel to- '6 each other behind the reflecting system, a.

collective lens disposed behind the reflec ing system, and an indicating device adaptt Z ed to indicate the distance apart of the axes of the said front lenses.

7. In a microscope fer measuring distances two front lenses disposed side by side and displaceable relatively to each other, a reflecting system, disposed behind the two front lenses and adapted to deflect the traversing luminous rays in such a way that the principal rays of the ray pencils emerging from the front lenses coincide with each other behind the reflecting-system in the and displaceable relatively to each other, a I

reflecting system consisting of two parts, of which one each lies behind one of the said two front lenses andis connected to it, the reflecting system being adapted to deflect the trawrsing luminous rays in such a way that the principal rays of the ray pencils emerg ing from the front lenses are parallel to each other behind the reflecting system in the pro' ection u on a plane, which contains the rays coinciding with the axes of the front. lenses, a collective lens disposed behind the reflecting system and an indicating device adapted to indicate the distance apart of the axes of the said front lenses.

9. In a microscope for measuring distances two semi-lenses disposed side by side in opposite direction and in such a way that their plane longitudinal surfaces substantially liein a plane, the two semi-lenses being dispaceable relatively to each other, a refleeting system consisting of two parts, of which one each lies behind one of the said semi-lenses and is connected to it, the reflecting system being adapted to deflect the traversing luminous rays in such a way. that the principal rays of the ray pencils emerging from the half lenses are parallel to each other behind the reflecting system in the projection upon a plane, which contains the rays coinciding with the axes of the half lenses, and the reflecting system admitting of approaching the two semi-lenses towards each other in such a'manner that the relative distance of their axes is smaller than its diameter. a collective lens disposed behind the reflecting system and' an indicating device adapted to indicate the distance apart of the axes of the said front lenses.

ALBERT KGNIG. 

